The invention relates to food products containing modified pea or lentil flour, and to processes for preparing them.
Substitutes for dairy based products have been developed in the food industry over many years. Plant protein based products offer advantages in terms of cost, nutritional properties, and accessibility, particularly in poorer countries.
Products based on legumes have been investigated. Soy bean in particular has been used to develop alternatives to dairy and meat products. Examples of soy products include tofu, imitation cheeses, meat analogs and non-dairy desserts. Over the years soy protein products have risen in price until they are nearly as costly as dairy and other high value proteins. This in turn has lead to exploration of cheaper alternatives such as pea flour.
The focus with both soy and pea products has been on value added fractions such as protein and starch isolates. The production of separate protein, carbohydrate and fibre by-products from legumes including peas and beans is described for example in U.S. Pat. No. 4,766,204. EP 0371725 provides methods for producing aerated food products using vegetable starch, including pea starch and stabilizers. EP 0639056 similarly uses vegetable starches to thicken foodstuffs.
Vegetable protein slurries including pea protein concentrates and their properties are described in Fleming S. E., et al. Journal of Food Science (1975) 40: 805-807. It is suggested that field pea concentrates and isolates may be useful as an alternative to soy protein where gelling ability is required. In Fernadez-Quintela et al. Plant Foods for Human Nutrition (1997) 4: 331-342, pea, soyabean and fava bean composition and functionality was investigated. Weak functional properties were identified. This reflects the applicants own findings that pea tofu prepared from a pea protein isolate formed only a small curd which was runny and easily disintegrated.
Slightly better results with pea flour to produce tofu were achieved by Gebre-Egziabher A. et al., Journal of Food Science (1983) 48: 375-377 and 388. The yield of curd from pea flour was about one third of that from soybeans. Moreover, the curd was grey in colour and soft in texture. Both colour and texture could be improved by addition of gluten. Gelling and coagulating properties of pea flour products other than curd were not investigated.
U.S. Pat. No. 5,296,253 describes the production of low moisture shelf stable products from legumes which requires two essential cooking steps while minimising shear. The first of the cooking steps is required to maintain the water content in the substrate. There was no investigation or recognition of the properties of pea or lentil substrates or effects of shear thereon in U.S. Pat. No. 5,296,253.
Specific food applications for pea protein isolate have been suggested. For example as dairy analogs. Chan ASM et al. (1992) Food Technology; January: p88-92; as a coconut cream alternative, EP 00679059, and as part of a dry beverage mix in H1620.
However, there has been little, if any, investigation into the properties of pea flour in its own right. This oversight may well be attributable to the unpleasant taste of pea flour, the fact that it is a low value product, and that soy has been a ready alternative. Therefore, utilities for pea flour identified to date are largely limited to its use as a thickener. See, for example, EP 00371725.
The present applicants therefore sought to investigate whether flours, including pea flour itself, as opposed to protein and starch concentrates and isolates could be used as a dairy and/or soy alternative. Surprisingly, the applicants found that pea and lentil flours have good gelatinising and coagulating properties not exhibited by other legume flours such as chickpea and soyabean flours, concentrates and isolates. The gelling properties make the pea and lentil flours suitable for use in a wide variety of structured food applications.
It is therefore an object of the present invention to provide a product suitable for use as a structured food or food analogue, which will at least provide the public with a useful choice.
There is also an increasing demand for foods which are not genetically modified. For example, soy protein, which has been used to make foods as soya tofu, is costly, regarded as universally genetically modified and contains antinutrients that are a concern for some consumers.
This may represent a further advantage of the products of the present invention.
Accordingly, in a first aspect the present invention provides a gelled food product comprising a stable gel matrix capable of holding bulk liquid formed from a starch and protein containing pea or lentil flour, wherein the flour starch has been gelatinised and the flour protein has been at least partially denatured and coagulated, and an added coagulating agent, wherein the coagulating agent is a di- or multivalent cation or salt thereof added in an amount of from about 0.06% by weight of the product; and with the proviso that the product does not include a hydrolysing enzyme.
Preferably, the flour is yellow pea flour.
Preferably, the product further comprises a source of lipid, most usually a vegetable oil or butter.
Preferably, the coagulating agent is desirably a di- or multi-valent metal salt, more preferably a calcium or magnesium salt.
The product may be in the form of either a solid or a semisolid.
In the above embodiments, the product preferably includes one or more flavouring agents.
The product may further include one or more additional additives or bio-active agents, such as vitamins, minerals, omega-3 lipids, and xe2x80x9chealthyxe2x80x9d microorganisms such as Bifidus sp and Acidophilus sp.
In a further aspect, the present invention provides a process of preparing a gelled food product comprising a stable gel matrix capable of holding bulk water, the process comprising:
forming a mixture of a liquid, an added coagulating agent and a starch and protein containing pea or lentil flour, wherein the flour starch is gelatinised and the protein flour is at least partially denatured and coagulated, wherein the coagulating agent is a di- or multivalent cation or a salt thereof and is added in an amount of from about 0.06% by weight of the product; with the proviso that no hydrolysing enzyme is used in the process.
Preferably, the flour is yellow pea flour.
Preferably, the mixture also includes a source of lipid, most usually a vegetable oil or butter.
It is also preferred that the coagulating agent is a di-valent or multi-valent metal salt, more preferably a calcium or magnesium salt.
In one preferred embodiment, the process comprises the following steps:
(i) mixing pea or lentil flour and liquid under conditions of shear and temperature sufficient to hydrate the flour and initiate gelatinisation of the flour starch;
(ii) heating the mixture to a sufficient temperature and for a sufficient time to complete starch gelatinisation and to denature the flour protein;
(iii) adding the coagulating agent to coagulate the denatured proteins; and
(iv) allowing the mixture to coagulate.
In a further preferred embodiment, the process comprises the following steps:
(a) mixing pea or lentil flour and water under conditions of shear and temperature sufficient to hydrate the flour and initiate gelatinisation of the flour starch;
(b) combining a source of lipid with the mixture under conditions of shear and temperature sufficient to form an emulsion;
(c) heating the mixture to a sufficient temperature and for a sufficient time to complete starch gelatinisation and to denature the flour protein;
(d) adding the coagulating agent to the mixture to coagulate the denatured proteins; and
(e) allowing the mixture to set into a gel.
As the reader will appreciate, the order of the steps in the process can be varied while still obtaining desired end products.
Preferably, in the processes the coagulating agent is a calcium or magnesium salt.
Preferably, the flour is yellow pea flour, which has preferably been subjected to a debittering process before use.
Preferably, in each of steps (i), (a) and (b) immediately above, the mixture is heated to a temperature of about 55-65xc2x0 C., more preferably about 60xc2x0 C.
Preferably, in step (ii) and (c), the mixture is heated to a temperature of about 73-100xc2x0 C., more preferably about 85-90xc2x0 C.
In another preferred embodiment, there is provided a process for producing a gelled food product comprising a stable gel matrix capable of holding bulk water, the process comprising:
extruding a mixture of a starch and protein containing pea or lentil flour, an added coagulating agent, and liquid under conditions of temperature and shear sufficient to gelatinise the flour starch and at least partially denature and coagulate the flour proteins, wherein the coagulating agent is a di- or multivalent cation or a salt thereof, and is added in an amount of from about 0.06% by weight of the product; with the proviso that no hydrolysing enzyme is used in the process.
Preferably, the flour is yellow pea flour.
Preferably, the mixture further includes a source of lipid. As above, a preferred protein coagulating agent is a calcium or magnesium salt.
In one embodiment, prior to the extrusion step (a), flour, water and protein coagulating agent are mixed together before the source of lipid is added.
Preferably, the extrusion is carried out at a temperature of about 73-180xc2x0 C.
In a further aspect, the present invention provides a food product obtained by, or obtainable by a process as defined above.
Also described is a gelling agent consisting essentially of a starch and protein containing pea or lentil flour, and an added coagulating agent, the native structure of the flour being modified sufficiently when a suitable liquid is added to produce a stable gel matrix, wherein the coagulating agent is a di- or multivalent cation or salt thereof, and is added in an amount of from about 0.06% by weight of a product to be formed, and wherein the flour modification comprises flour starch gelatinisation and flour protein denaturation and coagulation.
Preferably, the gel, sol or gelling agent further comprises a source of lipid.
While the invention is broadly as defined above, it is not limited thereto and also includes embodiments of which the following description provides examples.